Spectral Audio Decoding Using Intelligent Gap Filling for Bandwidth Extension
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Solution Overview
Problem
Current audio codecs face limitations in bandwidth extension techniques, which restrict high-frequency content reconstruction, leading to loss of detail and timbre, and require transformation into new domains, causing computational complexity and memory issues, especially in mobile devices.
Innovation Solution
The proposed solution involves performing bandwidth extension in the same spectral domain as the core decoder, allowing full-rate core decoding and using Intelligent Gap Filling (IGF) to regenerate spectral portions, eliminating the need for downsampling and upsampling, and enabling efficient filling of spectral gaps using parametric data and source spectral ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bandwidth extension techniques are used to reconstruct high-frequency content, then audio quality is improved, but transformation into new domains is required causing computational complexity and memory issues
Solution Approach 1:
The patent merges the bandwidth extension process with the existing MDCT spectral domain, eliminating the need for separate domain transformations. The high-frequency content is regenerated and filled directly within the same spectral representation used for core decoding, combining multiple functions into a unified processing framework that reduces computational overhead and memory requirements while maintaining audio quality improvements.
2Measurement precision
If bandwidth extension techniques are used to reconstruct high-frequency content, then audio quality is improved, but transformation into new domains is required causing memory issues
Solution Approach 1:
The patent combines the bandwidth extension data structures with the existing MDCT spectral arrays, using the same memory space for both core decoding and high-frequency regeneration. By operating entirely within the MDCT domain and reusing existing spectral buffers, the invention eliminates the need for separate memory allocations for domain transformations, significantly reducing overall memory consumption while delivering improved audio quality.
3Measurement precision
If spectral gap filling is performed using Intelligent Gap Filling, then spectral resolution is preserved, but parametric data processing is required
Solution Approach 1:
The patent implements self-service by having the decoder regenerate high-frequency spectral content autonomously using parametric side information and intelligent gap filling algorithms. The system uses the already-decoded low-frequency spectral data and transmitted parameters to automatically synthesize and insert the missing high-frequency components without requiring additional encoding or external processing, thereby preserving spectral resolution while managing processing complexity through efficient parametric representation.
Data Source
AI summary
An apparatus for decoding an encoded audio signal, includes a spectral domain audio decoder for generating a first decoded representation of a first set of first spectral portions, the decoded representation having a first spectral resolution; a parametric decoder for generating a second decoded representation of a second set of second spectral portions having a second spectral resolution being lower than the first spectral resolution; a frequency regenerator for regenerating every constructed second spectral portion having the first spectral resolution using a first spectral portion and spectral envelope information for the second spectral portion; and a spectrum time converter for converting the first decoded representation and the reconstructed second spectral portion into a time representation.